Lamps, and particularly halogen incandescent lamps for use in automotive headlights, are described, for example, in the referenced U.S. Pat. No. 4,412,273, Helbig et al. In this structure, a two-part base is used. The base includes a base core of plastic. A metallic base sleeve is retained in reception elements of the base core. The base core is comparatively complex and it has been found to present manufacturing difficulties.
The referenced British patent, assigned to the assignee of the present application, describes an automotive headlight-type lamp with a two-part base, in which the base core is made of ceramic. The ceramic base core and the base sleeve are coupled together by riveting. Some play may be left and the structure requires the additional rivet and the riveting part. The optical quality of an automotive headlight, however, is based largely on the quality of the attachment of the lamp to its base. As little play as possible should be used, so that the lamp will not go out of adjustment with respect to the focal point of the reflector. Ceramic materials are difficult to manufacture to close tolerances and, hence, a rivet connection which is tight and meets tolerance requirements is difficult to make.